On the application of cluster analysis for vegetation pollution assessment in the area of mining enterprise

The assessment of vegetation contamination in the influence area of mining enterprises is an important part of the research during the environment monitoring. There are different statistical methods that can be used for the analysis of data obtained in environmental monitoring. The article presents the results of cluster analysis of the chemical composition of agricultural vegetation samples collected in the area of copper-pyrite ore deposit location. During the analysis, all samples were divided into three clusters. One can suggest that this separation may be due to different mechanisms of pollutants entry into the particular sampling sites, as well as to the location of these sampling sites relatively to the enterprise industrial area. According to the results of the study, it can be concluded that cluster analysis is an effective tool for distinguishing the zones being characterized by different pollution mechanisms of grassy vegetation, when there are a small number of measurements and relatively low levels of the samples pollution. © 2019 Author(s)

Noncommutative Field Theories and (Super)String Field Theories

In this lecture notes we explain and discuss some ideas concerning noncommutative geometry in general, as well as noncommutative field theories and string field theories. We consider noncommutative quantum field theories emphasizing an issue of their renormalizability and the UV/IR mixing. Sen's conjectures on open string tachyon condensation and their application to the D-brane physics have led to wide investigations of the covariant string field theory proposed by Witten about 15 years ago. We review main ingredients of cubic (super)string field theories using various formulations: functional, operator, conformal and the half string formalisms. The main technical tools that are used to study conjectured D-brane decay into closed string vacuum through the tachyon condensation are presented. We describe also methods which are used to study the cubic open string field theory around the tachyon vacuum: construction of the sliver state, ``comma'' and matrix representations of vertices.Comment: 160 pages, LaTeX, 29 EPS figures. Lectures given by I.Ya.Aref'eva at the Swieca Summer School, Brazil, January 2001; Summer School in Modern Mathematical Physics, Sokobanja, Yugoslavia, August 2001; Max Born Symposium, Karpacz, Poland, September, 2001; Workshop "Noncommutative Geometry, Strings and Renormalization", Leipzig, Germany, September 2001. Typos corrected, references adde

Characterization of carbon contamination under ion and hot atom bombardment in a tin-plasma extreme ultraviolet light source

Molecular contamination of a grazing incidence collector for extreme ultraviolet (EUV) lithography was experimentally studied. A carbon film was found to have grown under irradiation from a pulsed tin plasma discharge. Our studies show that the film is chemically inert and has characteristics that are typical for a hydrogenated amorphous carbon film. It was experimentally observed that the film consists of carbon (~70 at. %), oxygen (~20 at. %) and hydrogen (bound to oxygen and carbon), along with a few at. % of tin. Most of the oxygen and hydrogen are most likely present as OH groups, chemically bound to carbon, indicating an important role for adsorbed water during the film formation process. It was observed that the film is predominantly sp3 hybridized carbon, as is typical for diamond-like carbon. The Raman spectra of the film, under 514 and 264 nm excitation, are typical for hydrogenated diamond-like carbon. Additionally, the lower etch rate and higher energy threshold in chemical ion sputtering in H2 plasma, compared to magnetron-sputtered carbon films, suggests that the film exhibits diamond-like carbon properties.Comment: 18 pages, 10 figure

Towards a Simple Model of Compressible Alfvenic Turbulence

A simple model collisionless, dissipative, compressible MHD (Alfvenic) turbulence in a magnetized system is investigated. In contrast to more familiar paradigms of turbulence, dissipation arises from Landau damping, enters via nonlinearity, and is distributed over all scales. The theory predicts that two different regimes or phases of turbulence are possible, depending on the ratio of steepening to damping coefficient (m_1/m_2). For strong damping (|m_1/m_2|<1), a regime of smooth, hydrodynamic turbulence is predicted. For |m_1/m_2|>1, steady state turbulence does not exist in the hydrodynamic limit. Rather, spikey, small scale structure is predicted.Comment: 6 pages, one figure, REVTeX; this version to be published in PRE. For related papers, see http://sdphpd.ucsd.edu/~medvedev/papers.htm

One-step fabrication of protonic ceramic fuel cells using a convenient tape calendering method

The present paper reports the preparation of multilayer protonic ceramic fuel cells (PCFCs) using a single sintering step. The success of this fabrication approach is due to two main factors: the rational choice of chemically and mechanically compatible components, as well as the selection of a convenient preparation (tape calendering) method. The PCFCs prepared in this manner consisted of a 30 μm BaCe0.5Zr0.3Dy0.2O3-δ (BCZD) electrolyte layer, a 500 μm Ni-BCZD supporting electrode layer and a 20 μm functional Pr1.9Ba0.1NiO4+δ (PBN)-BCZD cathode layer. These layers were jointly co-fired at 1350 °C for 5 h to reach excellent gas-tightness of the electrolyte and porous structures for the supported and functional electrodes. The adequate fuel cell performance of this PCFC design (400 mW cm-2 at 600 °C) demonstrates that the tape calendering method compares well with such conventional laboratory PCFC preparation techniques such as co-pressing and tape-casting. © 2020 by the authors.Russian Foundation for Basic Research, RFBR: 18-38-20063This work was supported by the Russian Foundation for Basic Research, grant number 18-38-20063. The authors thank G. Vdovin for his assistance in experiments. The SEM characterisation was carried out at the Shared Access Centre "Composition of Compounds" of the Institute of High-Temperature Electrochemistry [51]

Towards high-performance tubular-type protonic ceramic electrolysis cells with all-Ni-based functional electrodes

Protonic ceramic electrolysis cells (PCECs), which permit high-temperature electrolysis of water, exhibit various advantages over conventional solid oxide electrolysis cells (SOECs), including cost-effectiveness and the potential to operate at low-/intermediate-temperature ranges with high performance and efficiency. Although many efforts have been made in recent years to improve the electrochemical characteristics of PCECs, certain challenges involved in scaling them up remain unresolved. In the present work, we present a twin approach of combining the tape-calendering method with all-Ni-based functional electrodes with the aim of fabricating a tubular-designed PCEC having an enlarged electrode area (4.6 cm2). This cell, based on a 25 µm-thick BaCe0.5Zr0.3Dy0.2O3–δ proton-conducting electrolyte, a nickel-based cermet and a Pr1.95Ba0.05NiO4+δ oxygen electrode, demonstrates a high hydrogen production rate (19 mL min–1 at 600 °C), which surpasses the majority of results reported for traditional button- or planar-type PCECs. These findings increase the scope for scaling up solid oxide electrochemical cells and maintaining their operability at reducing temperatures. © 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of SciencesRussian Foundation for Basic Research, RFBR: 18-38-20063Council on grants of the President of the Russian FederationThis work was supported by the Russian Foundation for Basic Research (grant no. 18-38-20063 ). Dr. D. Medvedev is grateful to the Council of the President of the Russian Federation (scholarship no. СП−161.2018.1) for supporting the studies devoted to new MIEC materials. Other sections are performed within the framework of the budgetary plans of the Institute of High Temperature Electrochemistry